JPS5999025A - Supercharged internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain an excellent supercharging effect over the entire speed range of engine operation, by providing a first intake valve for feeding non-supercharged air and a second intake valve opened with some delay to the first intake valve and closed during the compression stroke of an engine in the cylinder head of the engine. CONSTITUTION:A first intake valve 25, a second intake valve 26 and an exhaust valve 30 are provided in an engine body 29, and the intake valves 25, 26 are provided respectively in a first and a second intake passages 22, 24. The first intake pipe 22 is connected directly to an air-flow meter 20 while the second intake pipe 24 is connected to the air-flow meter 20 by the intermediary of a compressor 23 of a small supercharger 27. Further, the exhaust valve 30 and a silencer 35 are connected together via a first exhaust pipe 31 having a turbine 28 of the supercharger 27 and a second exhaust pipe 33 having an exhaust-gas by-pass valve 32. Here, arrangement is such that the first intake valve 25 is opened during the suction stroke of an engine while the second intake valve 26 is opened with some delay to the first intake valve 25 and closed during the compression stroke of the engine.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a supercharged internal combustion engine, and has been improved so that a good supercharging effect can be obtained in the entire engine speed range, particularly in the low speed range of the engine. It relates to supercharged internal combustion engines.

[Prior art]

Matching the characteristics of the engine itself and the characteristics of the supercharger in a supercharged internal combustion engine is an important factor in determining the performance of the supercharged internal combustion engine. There are technical problems.

In general, making a supercharger more compact improves the performance of the engine at low speeds, but at high speeds it actually becomes a load on the intake air, reducing output and increasing fuel consumption even in non-supercharged engines. Become.

For this reason, conventionally, a large supercharger is generally installed in the engine at the expense of some low-speed performance. In addition, attempts have been made to provide both a small turbocharger for low speeds and a large turbocharger for high speeds, but this increases the size and weight of the entire device, increases manufacturing costs, and This is accompanied by problems such as the engine performance characteristic curve becoming discontinuous due to switching between two superchargers.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and uses a small turbocharger to obtain a good supercharging effect over the entire speed range of the engine including the low speed range, and also to reduce the size and weight of the entire device as well as cost reduction. The purpose is to provide a supercharged internal combustion engine that can contribute to the

[Summary of the invention]

The basic principle of the present invention is to divide the intake air amount of the engine into two, set the main air amount and the supercharging air amount, and create a small supercharger that is sufficient to supply the above supercharging air amount. The engine is configured so that it can supply supercharged air and simultaneously supply non-supercharged air, thereby achieving good engine performance over the entire speed range.

Therefore, the present invention provides a first intake valve that opens during the intake stroke of an internal combustion engine, and a second intake valve that opens later than the first intake valve and closes during the compression stroke. and a valve, and is configured such that supercharged air can be supplied through the second intake valve and non-supercharged air can be supplied through the first intake valve. shall be.

FIG. 1 is an intake and exhaust system diagram of an example of a conventional supercharged internal combustion engine for comparison. Exhaust gas discharged from the engine body 1 is introduced into a turbine wheel 5 of a supercharger 4 through an exhaust valve 2 and an exhaust pipe 3, and drives the turbine wheel 5 to rotate. By the rotation of the compressor wheel 6 integrally connected to the turbine impeller 5, the entire intake air amount of the engine body 1 is taken in from the air cleaner 7, and the intake pipe 8. The air is supplied to the combustion chamber A of the engine body 1 via the intake valve 9.

In order to suppress the peak pressure in the combustion chamber of the engine body 1, the supercharger outlet pressure is taken out from the branch pipe 8a of the intake pipe 8 to operate the actuator 10f, and the exhaust bypass valve 1 is activated.
1 and 7 to automatically control the rotational speed of the turbine wheel 5.

12 is a silencer.

Fig. 2 shows a compressor operation diagram of the conventional supercharger 4 configured as described above. It moves on the actuation line 13. For this reason, the high-speed range of the engine cannot be covered unless a large-capacity supercharger is installed. In this example, if we take the point where the engine rotational speed Ne=300 rpm, for example, the air flow rate (horizontal axis of this chart) is a little over 4 Ky/min.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIG.

Reference numeral 29 denotes an engine body, in which a first intake valve 25 and a second intake valve 26 are provided.

A first intake pipe 22 is provided between the air flow meter 20 and the first intake valve 25, and a second intake pulp 26 is provided in parallel with the first intake pipe 22.
A second intake pipe 24 is provided between the two, and a compressor 23 of a small supercharger 27 is interposed and connected in the middle of the second intake pipe 24.

Between the exhaust valve 30 of the engine body 29 and the silencer 35,
The first exhaust pipe 3 in which the turbine 28 of the small supercharger 27 is interposed
1 and a second exhaust pipe 33 provided with an exhaust bypass valve 32
and are provided in parallel.

The diaphragm actuator 34 that drives the exhaust bypass valve 32 receives the turbine inlet pressure Ptl or the compressor outlet pressure P of the /J'% type supercharger 27. 2 is configured to communicate with each other.

FIG. 4 is a chart showing the operation timing in the above embodiment, in which the horizontal axis shows the crank angle, and the vertical axis shows pulp opening/closing and the pressure in the combustion chamber of the engine body.

The lower half of this diagram depicts the opening area curves of the suction and exhaust pulp. Virtual i is the opening and closing operation of the exhaust pulp shown for reference, and as usual, the valve opens only during the exhaust stroke.

The solid line indicates the opening/closing operation of the first intake valve 25. The first intake valve, like the intake valve of a conventional internal combustion engine, opens a little before the top dead center of the intake stroke and closes a little after the bottom dead center of the intake stroke.

Now, if we operate the engine with only the first intake valve mentioned above, that is, with the second intake pulp 26 continuously closed and fc, the pressure change in the combustion chamber will be as shown by the solid line in the upper half of this chart. Become. This curve (solid line) is a pressure curve similar to that in a conventional non-supercharged internal combustion engine.

As shown by the dotted line in the lower half of this diagram, the second intake pulp 26 opens later than the first intake pulp 25 at the end of the suction stroke and closes in the middle of the compression stroke. Configure it as follows. During this period, the pressure in the combustion chamber increases from near atmospheric pressure to positive pressure, but the second intake pulp 26 is supplied with supercharged air (i.e. compressed air) from the supercharger 27. Therefore, the supercharged air overcomes the positive pressure within the combustion chamber and is forced to flow into the combustion chamber.

Due to the above action, when the first intake valve 25 and the second intake pulp 26 are used together, the pressure in the combustion chamber during the compression stroke becomes (
(solid line). This means that a large amount of gas is filled into the combustion chamber.

The above-mentioned filling gas is a mixture of gasoline and combustion air in a gasoline engine, and combustion air in a diesel engine.

As a result of filling a large amount of gas in the compression stroke, the combustion chamber pressure (dashed line) when the second intake valve is activated is:
In the expansion stroke, it becomes significantly higher than in the case of no supercharging (solid line). Therefore, the generated power increases.

As explained above, since the supercharged internal combustion engine of this embodiment draws in both non-supercharged intake air and supercharged intake air, the capacity of the supercharger can be significantly reduced.

As a result of making the turbocharger smaller, not only can the entire supercharged internal combustion engine be made smaller and lighter, reducing its manufacturing cost, but also the use of a smaller supercharger improves low-speed performance. Moreover, since non-supercharged intake air is also used, the output can be increased by adding the small supercharged engine output to the non-supercharged engine output without impeding engine performance even in the high-speed range.

The three effects mentioned above (a) improvement of low-speed performance, (b) maintenance of high-speed performance, and ←) miniaturization of the supercharger will be explained in detail below with reference to FIGS. 5 and 6.

The horizontal axis in FIG. 5 is the rotational speed of the engine. The upper half of the vertical axis in the figure shows the intake air amount, and the lower half of the vertical axis shows the shaft torque.

As shown in the upper half of this figure, the intake air amount of an internal combustion engine increases with the rotation speed in the case of a non-supercharged engine (double-dashed line), and in the case of a conventional supercharged engine (solid line), compared to the above-mentioned non-supercharged engine. However, in this embodiment (broken line), the result is as follows.

Equipped with a small turbocharger, it has good low-speed performance, and in the low-speed range, a significantly larger amount of air is taken in than a conventional supercharged engine (solid line).

Even in the high-speed range, the amount of intake without supercharging plus small supercharging is performed. That is, the curve marked with a dotted line in the upper half of FIG. 5 is the characteristic curve of the small supercharger. This curve shows good characteristics in the low speed range (approximately 2500 rpm or less), but the performance curve peaks out at medium speeds or higher (approximately 250 rpm or more).

The curve of this example (dashed line) is the curve of the non-supercharged engine (2
This is the result of adding the above small supercharger characteristic curve (dotted line) to the curve (dotted chain line). Therefore, in the low speed range, supercharging characteristics are significantly superior to those of conventional supercharged engines, and even in the high speed range (approximately 5,000 rl) m or higher), they are no worse than conventional supercharged engines (solid line). do not have.

As a result of obtaining the intake air amount as described above, the shaft torque of the engine becomes as shown in the lower half of Fig. 9, and the shaft torque (dashed line) of the supercharged engine of this embodiment is equal to that of the conventional supercharged engine. Compared to the shaft torque of the supplied engine (solid line), it is significantly superior in the low speed range and does not deteriorate even in the high speed range.

Further, as is clear from this graph, this example shows excellent performance in all speed ranges including low speed ranges, and does not have a discontinuous side/9rt- in the performance curve.

The engine characteristic curve shown in FIG. 5 described above represents a so-called full throttle condition, that is, a condition in which an appropriate load is applied to the engine output shaft. If the load is extremely light or there is no load, the rotational speed of the supercharger will not increase even if the engine rotational speed is high, and the supercharging effect will decrease in such a state. Looking at this in this chart, both the curve of the conventional supercharged engine (solid line) and the curve of this embodiment (broken line) approach the curve of the non-supercharged engine (double-dashed line). If there is no load, the engine will match the no-supercharging curve (double-dashed line) in the low speed range, and the supercharger will almost or completely stop in this state.

The above-mentioned changes occur automatically and smoothly in response to changes in load, and do not have any adverse effect on engine performance.

That is, since the purpose of installing a supercharger on an internal combustion engine is to increase the shaft torque, the supercharging effect is not required when the engine is under light load or no load.

FIG. 6 is a compressor operation diagram of the above embodiment. The engine operating line 13' has a shape as shown.

Even at an engine rotational speed of 3000 to sooorpm, the air flow rate is a little less than 2 Kf/min, and as shown in Figure 2, the air flow rate at 30001 m in a conventional supercharged engine is 4.
This is less than half compared to slightly more than 2000 kg/min.

As is clear from these graphs, by applying the present invention, it is possible to reduce the capacity of the supercharger to 1/2 or less, significantly improve low-speed performance, and not deteriorate high-speed performance.

FIG. 7 shows an embodiment different from the above, and the difference from the example shown in FIG.
This means that they are connected via an intervening connection. With this configuration, even if the pressure in the combustion chamber becomes higher than the discharge pressure of the compressor 23 while the second intake valve is open, there is no possibility that the intake gas will flow back into the second intake pipe 24.

In addition, if the engine output is increased by applying the present invention, and there is a risk that the main moving members of the engine will become mechanically or thermally stressed, the outlet pressure Pc2 of the compressor 23 of the small supercharger 27, or Turbine inlet pressure P t 1
is connected to the actuator 34 to connect the exhaust bypass pulp 32 to the actuator 34.
The structure is such that the rotation speed of the small supercharger 27 is suppressed by opening. Thereby, the operating conditions of the engine main body 29 can be reliably kept within a safe range. Further, the exhaust bypass pulp 32 may be configured to be linked to control system equipment (not shown) of the supercharged engine.

When using this embodiment, the supercharging pressure Pc2 or the turbine inlet pressure Pt1f may be given directly to the actuator 34 as a pressure signal as in this example, or it may be converted into an electrical signal via an appropriate sensor and sent to the actuator 34. 34 may be activated.

2. FIG. 8 shows an embodiment different from the above, and is an example of a supercharged internal combustion engine in which the present invention is applied to an injection type gasoline engine. The first intake pipe 22 and the second intake pipe 24 are provided with opening/closing pulps 54 and 55 for controlling the amount of air, respectively, and the injection valves 52.
53 is provided. The injection valve is a control unit 50
Each can be controlled independently. Further, the exhaust bypass pulp is controlled by a solenoid pulp 51 driven by an electric signal so that the rotational speed of the υ turbine wheel is kept constant.

FIG. 9 shows an embodiment in which the present invention is applied to a diesel engine, and 60 is a fuel injection nozzle.

As described above in detail, the supercharged internal combustion engine of the present invention has a first intake hole that opens during the intake stroke of the internal combustion engine, and a first intake hole that also opens later than the first intake hole to open during the compression process. The second valve closes during
an intake hole, and is configured to supply supercharged air to the second intake hole, and to supply non-supercharged air to the first intake hole. A good supercharging effect can be obtained over the entire speed range including the low speed range, and the overall supercharged internal combustion engine can be made smaller and lighter, resulting in an excellent practical effect of reducing manufacturing costs.

[Brief explanation of drawings]

Figure 1 is an example of the intake and exhaust system diagram inside a conventional supercharger, and Figure 2
The figure is a compressor operation diagram of the above-mentioned supercharged engine. 3 to 6 show an embodiment of the supercharged internal combustion engine of the present invention, FIG. 3 is an intake and exhaust system diagram, FIG. 4 is an operation timing diagram, and FIG. 5 shows performance characteristics of a conventionally equipped engine. 6 is a compressor operating diagram. FIGS. 7 to 9 are intake and exhaust system diagrams showing embodiments different from those described above. DESCRIPTION OF SYMBOLS 1... Engine body, 4... Supercharger, 22... First intake pipe, 23... Compressor of small supercharger, 24...
-Second intake pipe, 25...First intake pulp, 26...
2nd intake pulp, 27...Small supercharger, 2B...Small supercharger turbine, 29... Engine main body, 30...
Exhaust valve, 31... First exhaust pipe, 32... Exhaust bypass valve, 33... Second exhaust pipe, 34... Actuator, 35... Silencer, 51... Solenoid valve, 60 ...Injection nozzle. Agent Patent Attorney Masami Akimoto 1 Figure 2 Air flow rate Den (Rim Kinufu 3 Figure + Group $6 Figure! 4, Ji*'t-Qa (Kashi/-η)) Tea 7 Figure Figure 2

Claims (1)

[Claims] 1. A first intake valve that opens during the intake stroke of an internal combustion engine;
A second intake valve that opens later than the first intake valve and then closes during the compression process is provided, and supercharging air is supplied through the second intake valve, and A supercharged internal combustion engine characterized in that the engine is configured to supply non-supercharged air through the first intake valve. 2. The supercharged internal combustion engine according to claim 1, wherein the second intake valve is provided with a backflow prevention means between the intake air quality setting and the supercharger. . 3. The supercharger that supplies supercharged air to the second intake valve is provided with means for detecting the pressure within the intake pipe communicating with the second intake valve, and the above-mentioned detection means an exhaust bypass that is opened and closed based on at least one of the output signal of the supercharger, the detection signal of the exhaust gas pressure of the supercharger, and the signal representing the operational state of the internal combustion engine; A supercharged internal combustion engine according to claim 1 or 2, characterized in that the engine rotational speed is controlled so as not to exceed a certain value.